Challenges on the Way of Implementing TCP Over 5G Networks

Abstract

5G cellular communication, especially with its hugely available bandwidth provided by millimeter-wave, is a promising technology to fulfill the coming high demand for vast data rates. These networks can support new use cases such as Vehicle to Vehicle and augmented reality due to its novel features such as network slicing along with the mmWave multigigabit-per-second data rate. Nevertheless, 5G cellular networks suffer from some shortcomings, especially in high frequencies because of the intermittent nature of channels when the frequency rises. Non-line of sight state, is one of the significant issues that the new generation encounters. This drawback is because of the intense susceptibility of higher frequencies to blockage caused by obstacles and misalignment. This unique characteristic can impair the performance of the reliable transport layer widely deployed protocol, TCP, in attaining high throughput and low latency throughout a fair network. As a result, the protocol needs to adjust the congestion window size based on the current situation of the network. However, TCP is not able to adjust its congestion window efficiently, and it leads to throughput degradation of the protocol. This paper presents a comprehensive analysis of reliable end-to-end communications in 5G networks. It provides the analysis of the effects of TCP in 5G mmWave networks, the discussion of TCP mechanisms and parameters involved in the performance over 5G networks, and a survey of current challenges, solutions, and proposals. Finally, a feasibility analysis proposal of machine learning-based approaches to improve reliable end-to-end communications in 5G networks is presented. INDEX TERMS 5G, end-to-end reliability, mmWave, TCP ANNA CALVERAS AUGÉ was born in Barcelona, Spain, in 1969. She obtained a Ph.D. in Telecommunications Engineering from the Universitat Politècnica de Catalunya, Spain, in 2000. She is an associate professor at the mentioned University, at the Computer Networks Department, in the Wireless Networks Group (WNG). Her research interests and expertise areas comprise the design, evaluation, and optimization of communications protocols and architectures for cellular, wireless multihop networks, ad-hoc networks, wireless sensor networks, the Internet of Things, and application domains such as smart cities, building automation, satellite and emergency environments. She has been involved in several National and International research or technology transfer projects, and she has published in International and National conferences and journals.

How Sufficient is TCP When Deployed in 5G mmWave Networks Over the Urban Deployment?

“…The new generation can provide different use cases by relying on the vast available spectrum in high frequencies [3], [4]. However, due to the intermittent characteristic of mmWave, TCP cannot perform well and experiences performance degradation [5], [6]. The cause of this behavior is that as the frequency rises, its power in penetration objects declines.…”

“…A thorough investigation of TCP and 5G networks, their procedures, and parameters have been presented in [6]. The paper incorporates analysis of 5G networks, the functionality of TCP and how it performs over the new cellular networks, the existing advantages and disadvantages of 5G mmWave networks, the state-of-the-art of 5G networks, and how to deal with the problems in order to improve performance of TCP in 5G networks.…”

FB-TCP: A 5G mmWave Friendly TCP for Urban Deployments

“…By appearing new services and high-quality videos, exploiting high frequencies in 5G (Fifth Generation) is inevitable. As a consequence, millimeter-wave (mmWave) frequency bands are going to be deployed in the new mobile generation to provide high bandwidth for the wireless channels in order to fulfill the demand for large data rates [1], [2]. In addition to mmWave deployment, sophisticated spectrum management and a novel design for the core network are other enablers to support new features [3].…”

“…These features can support three primary use cases, including eMBB (Enhanced Mobile Broadband) to deliver high data rates, URLLC (Ultra-Reliable Low-Latency Communication) for satisfying latency-critical applications demands, and mMTC (massive Machine Type Communication) for providing connectivity to a large number of devices [4], [5]. The mmWave frequency suffers from a drawback called NLoS (Non-Line of Sight), which refers to a situation that a UE (User Equipment) and a gNB (gNodeB) cannot find each other because of an obstacle blocking the communication path [1], [2], [6]. When numerous NLoS to LoS (Line of Sight) transitions occur in a network, they can force performance degradation and reduce the quality of user experience.…”

“…When numerous NLoS to LoS (Line of Sight) transitions occur in a network, they can force performance degradation and reduce the quality of user experience. The principal reason is that reliable end-to-end communication relies on the protocol stack widely used transport protocol TCP (Transmission Control Protocol) [7], and without a suitable protocol that is able to exploit the 5G full potential, the wide bandwidth of mmWave will be wasted [2], [8]. So that one of the main pillars of the mmWave application relies on effective and sufficient TCP implementation [9].…”